Answer: The real answer is 40 degrees.
Explanation: However thats not an option, so be safe and go for 39
Because you may have Insomnia. Insomnia<span> is a sleep disorder that is characterized by difficulty falling and/or staying asleep. People with insomnia have one or more of the following symptoms: Difficulty falling asleep. Waking up often during the night and having trouble going back to sleep.</span>
Likely the chronological age, mainly because it would explain the differences in puberty stages between the two boys, which is an example of physical maturation.
If you mean why here you go then